Date: Tue, 6 Nov 2012 09:03:54 +0100
From: Michal Hocko <mhocko@suse.cz>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Glauber Costa <glommer@parallels.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, kamezawa.hiroyu@jp.fujitsu.com,
        Johannes Weiner <hannes@cmpxchg.org>, Tejun Heo <tj@kernel.org>,
        Christoph Lameter <cl@linux.com>, Pekka Enberg <penberg@kernel.org>,
        David Rientjes <rientjes@google.com>,
        Pekka Enberg <penberg@cs.helsinki.fi>,
        Suleiman Souhlal <suleiman@google.com>, JoonSoo Kim <js1304@gmail.com>,
        Andi Kleen <ak@linux.intel.com>
Subject: Re: [PATCH v6 19/29] memcg: infrastructure to match an allocation to
 the right cache
Message-ID: <20121106080354.GA21167@dhcp22.suse.cz>
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 <20121105162837.5fdac20c.akpm@linux-foundation.org>
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On Mon 05-11-12 16:28:37, Andrew Morton wrote:
> On Thu,  1 Nov 2012 16:07:35 +0400
> Glauber Costa <glommer@parallels.com> wrote:
> 
> > +static __always_inline struct kmem_cache *
> > +memcg_kmem_get_cache(struct kmem_cache *cachep, gfp_t gfp)
> 
> I still don't understand why this code uses __always_inline so much.

AFAIU, __always_inline (resp. __attribute__((always_inline))) is the
same thing as inline if optimizations are enabled
(http://ohse.de/uwe/articles/gcc-attributes.html#func-always_inline).
Which is the case for the kernel. I was always wondering why we have
this __always_inline thingy.
It has been introduced back in 2004 by Andi but the commit log doesn't
say much:
"
[PATCH] gcc-3.5 fixes
    
Trivial gcc-3.5 build fixes.
"
Andi what was the original motivation for this attribute?
 
> I don't recall seeing the compiler producing out-of-line versions of
> "static inline" functions

and if it decides then __always_inline will not help, right?

-- 
Michal Hocko
SUSE Labs
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